He is only half-kidding. Maybe less than half. When it comes to the tale of Martha Keyes and her daughter, Lucy -- whom one historian called ``the Lost Child of Wachusett Mountain " -- Stimpson is like a lot of folks in this small town: treading the line between belief and disbelief, torn between rationality and the lure of a compelling ghost story.

The difference is that Stimpson made a movie about it. ``The Legend of Lucy Keyes," a supernatural thriller starring Julie Delpy, Justin Theroux, and Brooke Adams, will air Saturday at 8 p.m. on the Lifetime Movie Network .

In a sense, the seeds for the film were planted in 1993, when Stimpson and his wife bought a house a stone's throw from the site where the Keyes home used to be. ``People would drive by and ask, `Is this the Lucy Keyes house?' " he recalls. ``And I'd say, `What are you talking about?' "

He found out soon enough.

On April 4, 1755, while apparently following her two sisters to Wachusett Pond, 4-year-old Lucy Keyes disappeared. She was never seen again. But her mother, Martha, never stopped searching for her. ``The stories are told that she flirted with insanity, that she would go out nightly in the woods, calling for her daughter," says Stimpson.

After Martha Keyes died in 1789, the legend began to build. Some came to believe that Martha's restless spirit was still abroad on the mountain, searching for her daughter. Some imagined that they could still hear the tormented mother at night, her voice carried on the wind, calling ``Luuuc y." Some still do. A local woman told Stimpson she had seen an apparition of a woman in Colonial garb on a mountain road. A groomer at the Wachusett Mountain Ski Area spoke of seeing fresh child-size footprints in the snow at 2 a.m.

``It's a tragedy that's sort of taken hold for 250-plus years," says Mary Cadwallader, president of the Princeton Historical Society. ``The lore is that people today still hear Martha calling Lucy in the mountains and other areas. I just talked to the third graders, and all they want to hear about is Lucy."

Perhaps it's understandable that the story of a lost child and a mother's unappeasable grief would reverberate through the years. The tale made its way into Stimpson's imagination and wouldn't let go. ``If you have any inclination toward belief in the spiritual world, the paranormal, this is the perfect situation," says Stimpson. ``A mother yearning in the afterlife for closure, and the fact that it's still unsolved."

Screening a legend

Though it is a work of fiction set in the present, Stimpson's film flashes back repeatedly to the real-life events that inspired it. Delpy and Theroux play Jean and Guy Cooley , who move to a small town with their two young daughters, one of whom is named Lucy. At the behest of a sinister developer played by Adams, Guy throws himself into persuading the townsfolk to support a wind-turbine energy project on Mount Wachusett. The smugly oblivious Guy ignores dire warnings from a local woman not to disturb the site where the spirit of Martha Keyes still searches for her daughter.

On the homefront, meanwhile, Jean is haunted by memories of another daughter, who was killed in a car accident. Soon the Cooleys are coping with another kind of haunting, as the film explores themes of guilt, both historical and personal, and about the hold the past has on the present.

So far, critics have split on ``The Legend of Lucy Keyes." Variety dismissed it as ``a modest psychological horror tale that could easily be dubbed `Amityville Jr.' " But Entertainment Weekly called it a ``beautifully filmed spookfest" that, while a ``slow build . . . still brings out the goosebumps." Stimpson says he is proud of the film, and while it is not receiving a theatrical release, he notes he has deals for either DVD releases (the DVD has already been released in the US) or TV airings in 25 countries.

In any case, this town 20 miles north of Worcester is buzzing about it. In a community of only 3,700, more than 1,000 showed up at an outdoor screening.

Many of them were probably hoping to see themselves in the movie. Stimpson, who wrote and directed the film, shot it mostly on location in Princeton and enlisted many locals as extras. In fact, when Stimpson addressed the crowd after August's screening, one disappointed extra whose scene was left on the cutting-room floor piped up with a question: ``How does it feel to be the one that cut his own son from the movie?" It was 15-year-old John Stimpson Jr., the filmmaker's oldest son, giving his old man the needle.

Local foundation

Stimpson grew up in Wellesley and attended Noble and Greenough and Harvard. After college, he went to Hollywood to try his hand at acting. He landed some work, mostly in TV commercials. He was one of a handful of finalists for the role of Woody in ``Cheers." He didn't get it and, weary of the insecurity of an actor's life, he turned toward filmmaking. He worked as a studio script reader , then returned east to a film production company in Boston, where he wrote scripts and produced corporate films. In 1988, he produced a documentary, ``Backstage at the Hasty Pudding," about the Harvard theatrical club. He codirected ``Beacon Hill" (2003) with former Massachusetts Secretary of State Michael Connolly. The movie was a flop, but it whetted his appetite to make another feature film.

He began writing the script for ``The Legend of Lucy Keyes" five years ago, and he shot most of the film over three weeks in 2004. Friends lent him the use of their house to serve as the Cooleys' s home. The Wachusett Mountain Ski Area, owned and operated by Stimpson's wife, Carolyn, and her two brothers, was the setting for some scenes. Cadwallader, of the historical society, showed him a doll believed to belong to Lucy Keyes, and he used a facsimile of that doll in the movie. The climax takes place in the muddy foundation of a home in the ski area that once belonged to John Greenleaf Whittier. ``I wrote the script knowing this location would be where we would wrap it up," says Stimpson, standing at the bottom of the circular stone foundation, which serves as a crypt in the movie.

Now that the story of Lucy Keyes has been translated through a filmmaker's sensibility, the movie will inevitably color thetale itself. Cadwallader, while praising the film and Stimpson's knowledge of local history, acknowledges that ``from a historical standpoint, even though it's a movie, we're probably for all time going to be fighting the truth versus the movie version."

Stimpson freely admits he changed a few details of the story, and he took the filmmaker's liberty of providing an answer to what happened to Lucy. But back in real life, the mystery continues to gnaw at him, and he can't help thinking about Lucy -- and Martha -- when he goes for a run or a hike on Mount Wachusett.

``I'll go into the woods, and I'll have the hair on the back of my neck up," he admits. ``Especially if it starts to get dark, I can't help but have my skin crawl."